Solvent deasphalting process
Through the non-critical three-stage extraction process and high-low pressure separation system, the problems of energy waste and sewage discharge in the solvent deasphalt process are solved, and efficient solvent recovery and purity improvement are achieved.
Patent Information
- Application Number
- CN202510806590.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-07-25
AI Technical Summary
In the existing solvent deasphalt process, the energy waste and sewage discharge problems caused by subcritical two-stage extraction have not been effectively solved.
A non-critical three-stage extraction process is adopted, and an independent high-pressure and low-pressure solvent recovery system is set up to optimize the solvent recovery process, and the solvent recovery is achieved through high and low pressure separation and steam stripping to achieve separate solvent recovery.
It reduces energy consumption and sewage discharge, improves separation efficiency and solvent purity, and reduces energy consumption and steam consumption of stripping towers.
Smart Images
Figure CN120365953A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solvent deasphalting, and particularly to a solvent deasphalting process. Background Art
[0002] Solvent deasphalting refers to a petroleum product refining process that removes resins and asphaltenes from the vacuum residue obtained by crude oil distillation by extraction, and produces petroleum asphalt while producing deasphalted oil; under the conditions of vacuum distillation, some high-viscosity wax oils or lubricating oil base components cannot be vaporized due to their very high boiling points and remain in the reduced residue oil. They are separated by utilizing the difference in solubility between them and resins and asphaltenes in the solvent. Conventional propane deasphalting and butane deasphalting usually adopt subcritical two-stage extraction, supercritical solvent recovery, and steam stripping in the stripping column to recover the solvent, resulting in energy waste due to the prior reduction and then increase in pressure of the low-pressure solvent recovery system, increasing energy consumption and sewage discharge. Summary of the Invention
[0003] The problem solved by the present invention is to provide a solvent deasphalting process that adopts non-critical three-stage extraction, and sets up an independent high-pressure solvent recovery system and low-pressure solvent recovery system to optimize the separate recovery of solvents, reducing energy consumption and sewage discharge.
[0004] To achieve the above object, the present invention adopts the following technical solutions: A solvent deasphalting process includes the following steps: Step 1, residue oil extraction; Step 2, high and low pressure two-stage separation; Step 3, solvent stripping recovery and product discharge. In Step 1, the residue oil from the tank farm is first premixed once, then the residue oil is heated, and after heating, it is premixed again. The oil extraction temperature is 100-120 °C, and the pressure is controlled at 4.5-5 MRa. The circulating solvent enters the middle and lower part of the extraction column and contacts the residue oil reversely. In Step 2, the deoiled asphalt flows out from the bottom of the column, is heated by heat exchange and heat transfer oil, pressurized by a booster pump and then enters the inside of the asphalt high-pressure separator, the temperature is heated to 160-190 °C, and the pressure is controlled at 4.9-5.5 MRa, so that the high-pressure solvent flows out from the top of the separator and enters the inside of the high-pressure solvent recovery system. The asphalt flowing out from the bottom of the asphalt high-pressure separator enters the asphalt low-pressure separator after heat exchange and heating by heat transfer oil, the temperature is heated to 250-280 °C, and the pressure is controlled at 1-1.2 MRa, so that the low-pressure solvent flows out from the top of the separator and then enters the inside of the low-pressure solvent recovery system, and the asphalt enters the stripping part. The effluent from the top of the extraction column enters the high-pressure settler after heat exchange and being pressurized by a heat transfer oil heating and pressurizing pump. The temperature is heated to 130 - 160 °C, and the pressure is controlled at 5 - 5.5 MRa. The deasphalted oil and part of the solvent flow out from the top of the settler. After being heated to 160 - 190 °C and the pressure is controlled at 4.5 - 5 MRa, they enter the high-pressure deasphalted oil separator; the high-pressure solvent at the top of the high-pressure deasphalted oil separator enters the high-pressure solvent recovery system. The deasphalted oil at the bottom is heated to 250 - 280 °C and the pressure is controlled at 1 - 1.2 MRa, then enters the low-pressure deasphalted oil separator. The low-pressure solvent at the top and the low-pressure solvent at the top of the deasphalted oil stripper tower enter the low-pressure solvent recovery system together; the effluent from the bottom of the low-pressure deasphalted oil separator enters the stripping section after heating. The effluent from the bottom of the high-pressure settler is gum and part of the solvent. After being heated to 160 - 190 °C and the pressure is controlled at 4.5 - 5 MRa, it enters the high-pressure gum separator. The high-pressure solvent at the top enters the high-pressure solvent recovery system; the effluent from the bottom of the high-pressure gum separator is heated to 250 - 280 °C and the pressure is controlled at 1 - 1.2 MRa, then enters the low-pressure gum separator. The low-pressure solvent at the top and the low-pressure solvent at the top of the gum stripper tower are sent to the low-pressure solvent recovery system together. The effluent from the bottom enters the gum stripping section after heating. In step three, the deasphalted oil, gum, and asphalt from their respective low-pressure separators enter their respective stripper towers for low-pressure solvent stripping. The stripping temperature is controlled at 250 - 280 °C, and the stripping pressure is controlled at 0.5 - 0.7 MPa; the solvent flows out from the top of the stripper tower to the low-pressure solvent recovery system. The deasphalted oil, gum, and asphalt products flow out from the bottom of their respective towers and are sent out of the device after heat exchange and cooling.
[0005] Preferably, in step one, the content ratio of n-butane in the solvent is 80% - 95%, and the content ratios of propane, isobutane, and isopentane are 0% - 10% respectively, so that the solution volume ratio is 5:1 - 6:1.
[0006] Preferably, in step two, the low-pressure solvent is condensed, pressurized, and then merged with the high-pressure solvent and recycled back to the extraction unit.
[0007] The beneficial effect of the present invention is that the process adopts a three-stage extraction process, which can enable better contact and mass transfer between the residue oil and the solvent. Solvent supercritical recovery adopts a solvent recovery process of two-stage separation of high and low pressures + steam stripping, and a high-pressure solvent recovery system and a low-pressure solvent recovery system are set up; the high-pressure solvent at the top of the high-pressure separator enters the high-pressure solvent recovery system, and the low-pressure solvent at the low-pressure separator and the top of the solvent stripper enters the low-pressure solvent recovery system; the low-pressure solvent is condensed, pressurized and then merged with the high-pressure solvent, and recycled back to the extraction unit; by setting up high and low-pressure separators and a solvent stripper in this process flow, the separate recovery of high-pressure solvent and low-pressure solvent is realized, avoiding the energy waste of a set of low-pressure solvent recovery system first reducing pressure and then increasing pressure; The device for optimizing solvent recovery greatly reduces the entrainment of heavy components in the solvent, improves the separation efficiency and solvent purity; the solvent carried by deasphalted oil, gum and deoiled asphalt when entering their respective strippers is greatly reduced. While ensuring product quality and separation efficiency, the steam consumption for stripping in the stripper is reduced by 50%; the energy consumption and sewage discharge are greatly reduced. Brief Description of the Drawings
[0008] Figure 1 is the process flow chart of the present invention; Figure 2 is the device flow chart of the present invention. Detailed Embodiments
[0009] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.
[0010] Specific embodiments are given below.
[0011] See Figures 1 - 2 , a solvent deasphalting process, including the following steps: including the following steps: Step 1, residue oil extraction; Step 2, two-stage separation of high and low pressures; Step 3, solvent stripping recovery and product discharge; In Step 1, the residue oil from the tank farm is first premixed once, and then the residue oil is heated. After heating, it is premixed again. The oil extraction temperature is 100-120 °C, and the pressure is controlled at 4.5-5 MRa. The circulating solvent enters the middle and lower part of the extraction tower and contacts the residue oil reversely; in Step 1, the content ratio of n-butane in the solvent is 80% - 95%, while the content ratios of propane, isobutane and isopentane are respectively 0% - 10%, so that the solution volume ratio is 5:1 - 6:1; In Step 2, the deoiled asphalt flows out from the bottom of the tower, is heated by heat exchange and heat-conducting oil, and enters the inside of the asphalt high-pressure separator after being pressurized by a pressure pump. The temperature is heated to 160-190 °C, and the pressure is controlled at 4.9-5.5 MRa, so that the high-pressure solvent flows out from the top of the separator and enters the inside of the high-pressure solvent recovery system. The asphalt flowing out from the bottom of the asphalt high-pressure separator enters the asphalt low-pressure separator after being heated by heat exchange and heat-conducting oil. The temperature is heated to 250-280 °C, and the pressure is controlled at 1-1.2 MRa, so that the low-pressure solvent flows out from the top of the separator and enters the inside of the low-pressure solvent recovery system. The asphalt enters the stripping section; The effluent from the top of the extraction tower enters the high-pressure settler after being heated by heat exchange and heat-conducting oil and pressurized by a pressure pump. The temperature is heated to 130-160 °C, and the pressure is controlled at 5-5.5 MRa. The deasphalted oil and part of the solvent flow out from the top of the settler and enter the deasphalted oil high-pressure separator after being heated to 160-190 °C and the pressure is controlled at 4.5-5 MRa; The high-pressure solvent at the top of the deasphalted oil high-pressure separator enters the high-pressure solvent recovery system. The deasphalted oil at the bottom is heated to 250-280 °C and the pressure is controlled at 1-1.2 MRa and then enters the deasphalted oil low-pressure separator. The low-pressure solvent at the top and the low-pressure solvent at the top of the deasphalted oil stripper enter the low-pressure solvent recovery system together; The effluent from the bottom of the deasphalted oil low-pressure separator enters the stripping section after being heated; The effluent from the bottom of the high-pressure settler is gum and part of the solvent. After being heated to 160-190 °C and the pressure is controlled at 4.5-5 MRa, it enters the gum high-pressure separator. The high-pressure solvent at the top enters the high-pressure solvent recovery system; The effluent from the bottom of the gum high-pressure separator is heated to 250-280 °C and the pressure is controlled at 1-1.2 MRa and then enters the gum low-pressure separator. The low-pressure solvent at the top and the low-pressure solvent at the top of the gum stripper are sent to the low-pressure solvent recovery system together. The effluent from the bottom enters the gum stripping section after being heated; In Step 2, the low-pressure solvent is condensed, pressurized and then merged with the high-pressure solvent and recycled back to the extraction unit; In Step 3, the deasphalted oil, gum and asphalt from their respective low-pressure separators enter their respective stripping towers for low-pressure solvent stripping. The stripping temperature is controlled at 250-280 °C, and the stripping pressure is controlled at 0.5-0.7 MPa; The solvent flows out from the top of the stripping tower to the low-pressure solvent recovery system. The deasphalted oil, gum and asphalt products flow out from the bottom of their respective towers and are sent out of the device after heat exchange and cooling.
[0012] This process adopts a three-stage extraction process, which can enable the residue oil and the solvent to achieve better contact and mass transfer; For the supercritical recovery of the solvent, a solvent recovery process of two-stage separation at high and low pressures + steam stripping is adopted, and a high-pressure solvent recovery system and a low-pressure solvent recovery system are set up; the high-pressure solvent at the top of the high-pressure separator enters the high-pressure solvent recovery system, and the low-pressure solvent from the low-pressure separator and the solvent stripping tower top enters the low-pressure solvent recovery system; the low-pressure solvent is condensed, pressurized and then merged with the high-pressure solvent, and recycled back to the extraction unit; by setting up high and low pressure separators and a solvent stripping tower in this process flow, the separate recovery of high-pressure solvent and low-pressure solvent is realized, avoiding the energy waste of a set of low-pressure solvent recovery system first depressurizing and then pressurizing. The device for optimizing the solvent recovery greatly reduces the entrainment of heavy components in the solvent, improves the separation efficiency and the solvent purity; the solvent carried by the deasphalted oil, gum and deoiled asphalt when entering their respective stripping towers is greatly reduced, while ensuring the product quality and separation efficiency, the steam consumption for stripping in the stripping tower is reduced by 50%; the energy consumption and sewage discharge are greatly reduced.
[0013] As mentioned above, it is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.
Claims
1. A solvent deasphalting process, characterized in that, It includes the following steps: Step 1, residue extraction; Step 2, two-stage separation of high and low pressure; Step 3, solvent stripping recovery and product discharge; In Step 1, the residue from the tank farm is first premixed once, then the residue is heated. After heating, it is premixed again. The oil extraction temperature is 100-120 °C, and the pressure is controlled at 4.5-5 MRa. The circulating solvent enters the middle and lower part of the extraction column and contacts the residue reversely; In Step 2, the deoiled asphalt flows out from the bottom of the column, is heated by heat exchange and heat transfer oil, and enters the inside of the asphalt high-pressure separator after being pressurized by a pressure pump. The temperature is heated to 160-190 °C, and the pressure is controlled at 4.9-5.5 MRa, so that the high-pressure solvent flows out from the top of the separator and enters the inside of the high-pressure solvent recovery system. The asphalt flowing out from the bottom of the asphalt high-pressure separator enters the asphalt low-pressure separator after being heated by heat exchange and heat transfer oil. The temperature is heated to 250-280 °C, and the pressure is controlled at 1-1.2 MRa, so that the low-pressure solvent flows out from the top of the separator and enters the inside of the low-pressure solvent recovery system. The asphalt enters the stripping part; The effluent from the top of the extraction column enters the high-pressure settler after being heated by heat exchange and heat transfer oil and pressurized by a pressure pump. The temperature is heated to 130-160 °C, and the pressure is controlled at 5-5.5 MRa. The deasphalted oil and part of the solvent flow out from the top of the settler, enter the deasphalted oil high-pressure separator after being heated to 160-190 °C and the pressure is controlled at 4.5-5 MRa; The high-pressure solvent at the top of the deasphalted oil high-pressure separator enters the high-pressure solvent recovery system. The deasphalted oil at the bottom is heated to 250-280 °C and the pressure is controlled at 1-1.2 MRa and then enters the deasphalted oil low-pressure separator. The low-pressure solvent at the top and the low-pressure solvent at the top of the deasphalted oil stripper enter the low-pressure solvent recovery system together; The effluent from the bottom of the deasphalted oil low-pressure separator enters the stripping part after being heated; The effluent from the bottom of the high-pressure settler is gum and part of the solvent. After being heated to 160-190 °C and the pressure is controlled at 4.5-5 MRa, it enters the gum high-pressure separator. The high-pressure solvent at the top enters the high-pressure solvent recovery system; The effluent from the bottom of the gum high-pressure separator is heated to 250-280 °C and the pressure is controlled at 1-1.2 MRa and then enters the gum low-pressure separator. The low-pressure solvent at the top and the low-pressure solvent at the top of the gum stripper are sent to the low-pressure solvent recovery system together, and the effluent from the bottom enters the gum stripping part after being heated; In Step 3, the deasphalted oil, gum, and asphalt from their respective low-pressure separators enter their respective stripper columns for low-pressure solvent stripping. The stripping temperature is controlled at 250-280 °C, and the stripping pressure is controlled at 0.5-0.7 MPa; The solvent flows out from the top of the stripper column to the low-pressure solvent recovery system. The deasphalted oil, gum, and asphalt products flow out from the bottom of their respective columns, and are sent out of the device after heat exchange and cooling.
2. The solvent deasphalting process according to claim 1, wherein, In Step 1, the content ratio of n-butane in the solvent is 80%-95%, while the content ratios of propane, isobutane, and isopentane are 0%-10% respectively, and the solution volume ratio is 5:1-6:
1.
3. A solvent deasphalting process according to claim 1, characterized in that, In the second step, the low-pressure solvent is condensed, pressurized and then merged with the high-pressure solvent, and then recycled back to the extraction unit.